Telephone system



y 3 1933- R. L. STOKELY, 1,910,972

TELEPHONE SYSTEM Filed July 1, 1932 3 Sheets-Sheet l Q "3 v 5% Q5 Q k xI I I l I INVENTOR R.L..STO/(ELV 6 BY- t 747W? A T7'ORNEY y 23, 3- R. L.STOKELY 1,910,972

TELEPHONE SYSTEM Filed July 1, 1932 3 Sheets-Sheet 2 INVENTOR R.LSTO/(ELY ATTOR/VE Y FIG. 2

TELEPHONE SYSTEM Filed July 1, 1932 3 Sheets-Sheet 3 INVENTOR By R.LSTOKEL) ATTQRNW r Patented May 23, 1933 UNITED sures PATENT. OFFICE BAYL. srom'r, OF mm'rm m YORK, ASBIGNOB TO BELL TELEPHONE LABO- EJ303138,IHWBPOWD, OI TORI, N. Y., A CORPORATION 01! NEW YORK srsrmr ApplicationMel mu; 1, a. Serial Io. 680,887.

This invention relates to telephone systems and more particularly toautomatic telephone systems having multi-station The object of thisinvention is to simplify the equipment required in automatic telephonesystems for providing party line service and to provide an arrangementfor the more efiicient and economical use of this equipment.

Heretofore, automatic telephone systems have been arranged so that asubscriber on a party line can call another station on the same line. Incertain of these systems, the switches employed in completingconnections between subscribers on difierent lines are also employed incompleting connections between stations on the same line, in which casethe final switch is arranged to make a-reverting busy test to determinewhether the called line is busy on account of being the same line asthat which serves the calling station. In other systems, a special. ringback switch is employed to signal the called and calling stations. Ineither case the ringing of the called station is initiated by replacingthe receiver at the calling station,v and talkin battery is thenfurnished from the fina switch or the special ring back switch; or, insome cases the talking battery is furnished from the first selector, allother switches involved in the connection being released.

In a system arranged according to this invention, all of the switchesused in establishing a desired connection are released when the line ofthe called station is also the line of the calling station. To this endthe subscribers line circuit is arranged to supply talking battery tothe calling and called stations upon receiving an indication from thefinal selector that these stations are on the same line. The finalselector is arranged to seize the terminals of the line, to make theusual reverting busy test, to determine whether the call is a revertivecall, to ring both the calling and called stations, to signal the linecircuit that the call is a revertive call, and to cause the release ofall of the switches involved in the completion of the call. The linecircuit maintains the talking connection without causing furtheroperation of the central office switches until 1: e rece vers have beenreplaced at both of the calllng and called stations; whereupon the linecircuit is again rendered effective for the initiation of a call fromany of the stations which it serves.

In a system arranged to complete revertive calls by extending theconnection to a ring back switch instead of using a final selector toseize the line and signal the stations, the ring back switch can bearranged to signal the line circuit that the call is a revertive calland to thereupon cause the release of the switches involved.

A telephone system arranged in accordance with the features of thisinvention is ,shown diagrammatically in the drawings which consist offour figures.

Fig. 1 shows a party line with subscribers stations A and B, theassociated line circuit LC, and a line finder switch LF.

Figs. 2 and 3 show a connector switch SC with its associated controlequipment, and a third subscribers station 0.

Fig. 4 shows how Figs. 1, 2 and 3 are to be arranged with respect toeach other.

The line finder and connector switches illustrated in the drawings aresimilar in construction, both being of the Strowger type. For a completedescription of the Strowger type connector switch, reference may be hadto pages 53 to 56, inclusive, of the second edition of AutomaticTelephony by Smith and Campbell. The invention is not limited, however,in its application to systems using this particular type of switch noris it limited to the particular system shown in the drawings.

The line finder switch is represented schematically by the brushes 11,12, 13 and 14; the driving magnets and other equipment associated withthe switch are omitted since a clear and complete description of theinvention may be made without including the detailed operation of theline finder switch. For a description of the operation of a Strowgertype line finder, reference may be had to the patent to H. Hovland,1,711,682, May 7, 1929; the brushes 11,12 and 13 of the drawin s may beeither one of the two sets of brushes shown in this patent.

The connector switch SC is designed for use in a small dial centralofiice having ten party lines and is arranged for code ringing and forcompleting reverting calls. It is also arranged to function as aselector on certain levels and to function as a rotary hunting connectorfor completing calls to lptrivate branch exchanges on other levels. eoperation of the switch as a selector or a rotary hunting connector willnot be described in detail since the invention is concerned only withthe establishing of reverting calls, that is, calls from one station ona line to another station on the same line.

The connector switch includes the brushes 41, 42, 43 and 44, thevertical stepping magnet 45, the vertical off-normal springs 46, therotary stepping magnet 47 and the rotary off-normal springs 48. Otherequipment associated with the connector switch includes relaysdesignated 21 to 38, inclusive, the tone supply transformers 50 and 90,a start magnet 80 for starting operation of the ringing machinecomprising interrupter drums 81 to 87, inclusive, and an auxiliaryrotary switch CS comprlsing the steppin magnet 70, brushes and banks 71and 72, o normal springs 73 and release magnet 74.

Operatlon of the system shown in the drawings will be illustrated byassumin calls from station A to stations B and When the subscriber atstation A removes the receiver to originate a call, the line relay 2operates. The circuit for operating relay 2 is traced from batterythrough the middle winding of relay 2, outer lowercontact of cut-oilrelay 4, over the lower conductor of line 1, through the subscribers setat station A, back over the upper conductor of line 1, outer uppercontact of relay 4, and'through the lower winding of relay 2 to ground.Relay 2 connects a marking potential to the test terminals of line 1 inthe banks of the line finders common to line 1. This connection may betraced from battery through the winding of relay 4 and from batterythrough the winding of resistance 3, through the inner front, contactsand upper winding of relay 2, over conductor 7, through the upper backcontact of relay 6, to the test terminal in the bank of swltch LF. Relay2 also closes a circuit from ground through its uppermost front contact,through the inner lower back contacts of relays 6 and 4, and through thewinding of group relay 5, to battery. ,Relay 5, which is common to alllines in the same group with line 1, operates to cause an idle linefinder switch to search for the calling line.

Assuming that the switch LF is the one used on the call in question, thebrushes 11, 12, 13 and 14 are stepped up to the level in which theterminals of line I are located and are then rotated until the testbrush 13 engages the test terminal of line 1. During the rotation, thetest brush 13 is connected to ground (not shown) thereby causing theoperation of the cut-off relay 4 and the stopping of the line finderbrushes in the usual manner. When relay 4 operates, the conductors ofline 1 are dlsconnected from the windings of, relay 2 and extendedthrough brushes 11 and 12, thereby causing the operation of the linerelay 21 of the connector switch C. The circuit for operating relay 21is traced from battery through the inner lower back contact of relay 36,upper winding of relay 21, inner lower back contact of relay 27,next-to-the-outer lower back cont-act of relay 38, lowermost backcontact of relay 36, conductor 16, through brush 12 of line finder LF,lower front contact of relay 4, over line 1 and through the subset atstation A, uppermost front contact of relay 4, brush 11 of line finderLF, conductor .15 next-to-the-outer upper back contact of relay 38,outer lower back contact of relay 27, lower winding of relay 21, middlelower back contact of relay 36, upper back contact of the verticaloil-normal springs 46, through the left winding of dial tone transformer50, to ground. Relay 21 closes an obvious circuit for operating relay22; and relay 22 connects a holding ground at its uppermost frontcontact through the nextto-the-inner lower back contact of relay 38, tothe test conductor 19 of line finder LF to hold this switch until theentire connection is to be released. The holding ground is furtherextended from conductor 19 through test brush 13 to the test conductorof line circuit LC to hold the cut-off relay 4 operated. The line relay2 releases when the cut-off relay 4 operates, rela 4 being lookedthrough its inner upper ront con tact to the holding ground on conductor19. The upper front contact of relay 4 is also effective toshort-circuit the upper winding of relay 2, this winding havingprevented the release of relay 2 until the cut-off relay 4 is locked tothe holding ground. The release of relay 2 causes the release of relay5. The aforementioned operation of relay 22 also closes a circuitthrough the lower winding of relay 37. Relay 37 operates, therebyclosing a circuit from ground at the inner upper back contact of relay38, through the upper back contact of relay 27 the inner lower frontcontact of relay 37, and through the winding of start magnet 80 tobattery.

The operation of magnet 70 starts the ringrentimpulses created by thedialing of the first digit of the called number, relay 21 is alternatelyreleased and reoperated. The first release of relay 21 closes a circuitfor operating'the rela 23 and the vertical step- Elllg magnet 45. hiscircuit is traced from attery, through the winding of relay 23, thelowermost back contact of relay 28, winding of magnet 45,next-to-the-outer lower front contact of rela 37, lower back contact ofthe vertical 0 -normal springs 46, to ground at the back contact ofrelay 21. In operating, magnet 45 steps the brushes 41, 42, 43 and 44 upto the first level of the terminal bank and the vertical oil-normalsprings 46 are actuated when the switch moves out of its normalposition. With the springs 46 actuated and with relay 23 operated, thedialin circuit is traced from ground through t e u per front contact ofsprings 46 instead of throu h the left winding of the dial tone transormer 50 and is traced through the lower front contact of springs 46,the outer lower front contact of relay 37 and the outer front contact ofrelay 23 instead of through the next-to-the-outer lower front contact ofrela 37. When relay 21 reoperates after the rst impulse, magnet 45releases but relay 23 is slow in releasing and remains operated untilall of the impulses in the series have been received. Relay 22 is alsoslow in releasing and remains operated during the receipt of dialimpulses. Each succeeding release and reoperation of relay 21 causes theoperation and release of magnet 45 thereby step ing the brushes ofswitch SC u to the evel correspondin to the first dig1t of the callednumber. Re ay 23, after all of the first series of impulses have beenreceived, releases thereby rendering the rotary steppm magnet 47responsive to the next series 0 dial impulses received from the callingstation.

When the second digit of the called numher is dialed, relay 21 is a ainalternately released and reoperated. he first release of relay 21 iseffective to operate magnet 47 and relay 25 in a circuit which is tracedfrom ground at the back contact of relay 21, through the lower front.contact of sprin s 46, lowermost front contact of relay 3 outer backcontact of relay 23, inner lower back contact of relay 38, conductor 51,next-to-the-lowermost back contact of relay 34, inner lower back contactof relay 35, windin of magnet 47, windin of relay 25, and t rough the uper bac contactof relay 33 to battery. he operation of magnet 47 stepsthe brushes 41, 42, 43, 44 into contact with the first set of terminalsin the selected level. The operation of relay 25 renders the circuit formagnet 47 independent of relay 34, the outer front contact of relay 25being in parallel with the next-to-the-lowermost back contact of relay34. Relay 25 also connects the windmg of test relay 24 to the test brush43. This connection is traced from battery through the winding of relay24, lowermost back contact of relay 35, inner front contact of relay 25,conductor 39, to brush 43. As soon as the brushes are moved out of theirnormal rotary position, the rotar oif-normal sprm 48 are actuated, therey closing a circuit rom battery through the winding of relay 34, frontcontact of springs '48, uppermost back contact of relay 35, conductor56, to ground at the middle lower front contact o relay 37. Relay 34operates in this circuit and locks through its inner upper front contactand the next-to-the-inner upper back contact of relay 38, inner lowerack contact of relay 33, over conductor 56 to the same ground at relay37. When rela 21 reoperates, magnet 47 releases but re ay 25 is slow inreleasing and remains operated until all of the impulses created by thedialingEof the second di it have been received. ach succeeding re easeand reoperation of relay 21 causes the operation and release of magnet47 thereby step in the brushes to the set of terminals wliic correspondsto the number dialed. If the called line is busy, a guarding groundpotential is encountered on the test terminal of the called line and thetest rela 24 operates before relay 25 releases. elay 24 looks, throughits middle upper front contact and the upper back contact of rela 29 tothe busy ground on conductor 39. en relay 25 re cases, a circuit isclosed from battery through the winding of relay 33, contacts of magnet47, conductor 55, back contact of the continuity springs of relay 33, upermost front contact of relay 24, outer bac contact of relay 25, windingand upper back contact of relay 29 to the ground on conductor 39. Relay33 is marginal and does not operate but relay 29 o erates in thiscircuit, the front contact 0 the continuity springs of relay 29 beineffective to close a holding circuit for itself and for relay 24, overconductor .53 to ground at the next-to-the-inner'lower front contact ofrelay 37. Relay 29 connects the left winding of busy-tone transformer toone side of condenser 68, thereby transmitting a busy tone through thiscondenser and through back contacts of relays 38 and 36 over conductor16 to the calling station.

Assuming that line 99 is the called line and that it is idle, relay 24does not operate and the release of relay 25 closes a circuit frombattery through the winding of the cut-oif relay (not shown) and testterminal of line 99, through brush 43, conductor 39, inner back contactof relay 25, lower winding of relay 35, back contact of relay 24, overconductor 56, to ground at relay 37.

Relay 35 is sufficiently energized by the current in this circuit toclose its inner upper front contacts and thus complete its operation byenergizing its upper winding in a 5 circuit through these contacts andover conductor 53 to ground at relay 37 When fully operated, relay 35connects the ground on conductor 56 throu h its middle u per frontcontact over con uctor 39 to brus 43 to prevent the seizure of line 99by another connector.

When the calling subscriber dials the party designation 0 the calledsubscribers station, relay 21 again alternately releases and reoperates.The first release of relay 21 closes a circuit from ground at its backcontact, through the lower front contact of springs 46, the lowermostfront contact of relay 37 the outer back contact of relay 23,

the inner lower back contact of relay '38, conductor 51, the middlelower back contact of rela 25, next-to-the-uppermost front con tact orelay 34, back contact of the off-normal springs 73 of the code switchCS, next- 25 to-the-inner upper front contact of relay 34, conductor 54,inner front contact of relay 22, and through the winding of the steppingmagnet 70 to battery. Relay 32 operates in parallel with the magnet 70,a connect-ion being traced from the winding of relay 32 through theinner upper back contact of relay 36 to conductor 54. The opera tion ofma net 70 advances the brushes 71 and 72 to t eir first off-normalosition and actuates the off-normal springs 3. The operation of relay 32renders the circuit for itself and magnet 70 independent of theoilnormal contacts 73; this circuit now being traced from conductor 54,through the inner upper front contact of relay 32, over conductor 52,and through the middle lower back contact of relay 25 to conductor 51and thence to ground at the back contact of relay 21 as hereinbeforedescribed. Relay 32 is slow in releasing and remains operated during thereceipt of all of the impulses in the series but the magnet 70 isalternately operated and released by the alternate release andreoperation of relay 21 in response are thus advanced to a positioncorresponding to the party designation of the called station.

When relay 32 releases after all the party designation impulses havebeen received, the winding of pick-up rela 33 is connected through theback contact 0 magnet 47, conto the dial impulses. The brushes 71 and72' front contact and the lowermost front contact of relay 34, overconductor 53, to ground at relay 37. Relay 34 now releases since itsoperating circuit was opened by relay 35 and its holding circuit isopened by relay 33. The release of relay 34 closes a circuit foroperating rela 28. This circuit is traced from battery t rough thewinding of relay 28, lowermost back contact of relay 34, inner lowerfront contactof relay 35, inner lower back contact of relay 26, toground on conductor 19. Relay 28 closes a holding circuit through theupper winding of relay 37 The release of relay 34 is also effective toclose the ringing c1rcuit to signal the called station. Assuming thecode switch to be set in position2, the ringing circuit may be tracedfrom the source of superim osed ACDC ringing current 88 thorug theringin interrupter 81, second terminal and brush 1, inner upper backcontact of relay 34, uppermost back contacts of relays 26 and 38,uppermost front contact of relay 35, brush 41, upper conductor of line99 through the condenser and ringer at station C to ground. Theinterrupter 81 controls the ringing circuit so that a 2-ring code istrans mitted over the upper conductor of line 99 to operate all of theringers connected to that conductor. Ringing tone is transmitted to thecalling station through condensers 65 and 67. The two rings are repeateduntil the receiver is removed at the called station at which time theringing current circuit is extended back over the lower conductor ofline 99, through brush 42, lowermost front contact of relay 35,lowermost back contacts of relays 38 and 26, inner lower back contact ofrelay 34, brush 72 and second terminal, upper back contact of relay 32,and through the lower winding of relay 26 to ground. Relay 26 operates,looks through its upper winding and inner upper front contact overconductor 53 to ground at relay 37, (Fens the ringing circuit,disconnects ground m the start conductor to permit the release of startmagnet 80, and completes the talking connection between .stations A andC. Talking battery is supplied to the called station in a circuit whichmay be traced from battery at the inner lower back contact of relay 36,lower winding of supervisory relay 27 upper front contacts of relay 26,uppermost ack contact of relay 38, uppermost front contact of relay 35,brush 41, line 99 and subset at station C, brush 42, lowermost frontcontact of relay 35, lowermost back contact of relay 38, lowermost frontcontact of relay 26, upper winding of relay 27, inner lower frontcontact of relay 26, to ground on conductor 19. Relay 28 is slow torelease and before it can release due to the opening of talking currentis transmitted through condensers 67 and 68.

When the connection is released by replacing the receiver at station A,relays 21, 22

' and 37 release in the order named. The release of relay 22 disconnectsground from conductors 17 and 18, thus removing the holding potentialfrom test conductor 19. The cut-oil relay 4 inline circuit LC is thusreleased so that another call may be initiated or completed over line 1.The line finder LF is also restored to normal in the usual manner whenthe holding potential is disconnected from conductor 19. The release ofrelay 37 disconnects ground from conductors 53 and 56 causing therelease of reays 26 and 35. When the receiver is replaced at station C,relays 27 and 28 release in the order named. The release of relay re--moves the busy potential from the sleeve terminal of line 99 and closesa circuit from release magnet circuit being '0 battery throughthewinding of release magnet 49 of switch SC, inner upper back contact ofrelay 35, lowermost back contact of relay 37, lower front contact ofvertical ofinormal springs 46, to ground at back contact of rela'y 21.The operation of magnet 49 causes the shaft and brushes of switch ,SC 3

to be returned to'their normal position, the

springs 46. The release of relay 3 closes a circuit from battery throughthe release magnet 74 of 'code switch GS, next-to-theinner lower backcontact of relay 34, lower front contact of ,ofi-normalsprings 73, up-

permost back contact of relay 34,to ground at the inner lower backcontact of relay The operation of magnet 74 causes the brushes ofswitchCS to be restored to normal position, the release magnet circuit beingopened at s rings 73.

Assume now t at station is calling station B, both of these stationsbeing, connected to line 1. The connection is extended from line 1through line finder LF to the connector SC which responds to the dialingof the number and party designation of the called station in the samemanner as hereinbefore described. The brushes 41, 42, 43 and 44 are inthis case advanced to engage the terminals in its bank; which connect toened at is connected through brush 13 of line finder LF to the ground onconductor 19. Relay 29 :is' operated, relay 24 is held operated, thecalling subscriber receives a busy tone, and the code switch CS ispositioned by the dialing of the party designation, all in the mannerhereinbefore described. When the calling a subscriber replaces the.receiver on the re-' ceiver hook to permit the ringing of the calledstation B, relays 21 and 22 release in the order named. Relay 37 is.held operated by a circuit from battery through its upper winding, outerlower front contact of relay 29, conductor 18, next-to-the-inner lowerback contact of relay 38, conductor 19, line finder brush 13, the upperback contact of relay 6 in the line circuit LC, inner upper frontcontact of relay 4, lowermost back contact of relay 6 conductor 10,brush 43 of the connector 80, conductor 39, upper most front contact ofrelay 37, lowermost back contact of relay 32, inner lower front contactof relay 34, lower front contact of springs 73, next-to-the-outer upperfront contact of relay 34, middle back contact of relay 25, conductor-51, inner lower back contact of relay 38, outer back contact of relay23, lowermost front contact of relay 37,

lower front contact of springs 46 toground at the back contact of-relay21. Thus re-v la L% are held in their operated. position by thecurrentin this circuit over, conductor 37, the cut-oi'r'relay 4 and the linevfinder 10 to the ground supplied from the back contactofi relay 21, Theground thus. connected to conductor 19 is ;also extended through thenext-to-the-inner lower back contact of relay 38, over conductor 18,.and

v through the backgcontact of .relaya22, the,

inner upper fronticontactoi relay 37 and .105 the back contact of'relay31, to the winding a vof relay 36. Relay 36 operates to open theconnection over conductor 16 to the line finder and closes a circuitfor'operating'relay 35; this circuit is traced from battery through theupper winding of relay 35, up-

permost front contact ofrelay 36,.over con-,- ductor 53 to groundatrelay 37. ,Relay 35 g closes the connection for [operating relay 33 toground at the pick-up interrupter 8.6 and connects the conductors 8 and9t-hrough to.

the contacts of the tripping relay 26. Relay 33 is operated and relay 34released as hereinbefore described to start the ringing.

Ringing current is connected to one side ofline 1 to signal the. calledstation with the proper ringing code and is also connected to the otherside of the line to transmit two short impulses for each codecycle tooperate the ringers connected to said other side. If the ringer of thecalling station is not connected to the same side of the line as thecalled station, the termination of the short impulses informs thecalling station that the called station-is being signaled-and sincethese impulses cease when the called party answers, the callingsubscriber knows when to a ain remove the receiver for thepurpose 0conversing with the called subscriber. Assuming the party designation ofstation B to be 3, the code switch CS is in position 3 and the circuitfor signaling the called station is traced from the source of ringingcurrent 88 through interrupter 82, terminal 3 and brush 72, inner lowerback contact of relay 34, lowermost back contacts of relays 26 and 38,lowermost front contact of relay 35, brush 42 of switch SC, conductor 9,lower front contact of cut-off relay 4, lower conductor of line 1,through the condenser and ringer at station B to ground. The circuit forsignaling the stations with ringers connected to the upper conductor ofline 1 is controlled by relay 32, the circuit for intermittentlyoperating this relay being traced from battery through its winding, theinner upper front contact of relay 36, conductor 54, thenext-to-the-inner lower back contact of relay 34, to interrupter 87.Relay 32 is momentarily operated to ground at interrupter 87 twice pereach code cycle, each operation of relay 32 being efiective to close acircuit from ringing source 88 through the outer upper front contact ofrelay 32, terminal 3 and brush 71 of the code switch, inner upper backcontact of relay 34, uppermost back contacts of relays 26 and 38,uppermost front contact of relay 35, brush 44 conductor 8, uppermostfront contact of relay 4, over the upper conductor of line 1, throughthe ringer at station A to ground.

When the subscriber at the called station removes the receiver to answerthe call, the ringing circuit is extended back over the upper conductorof line 1, over conductor 8, through brush 41, contacts of relays 35, 38and 26 in the order named, inner upper back contact of relay 34, brush71 and terminal 3, upper back contact of relay 32, through the lowerwinding of relay 26 to ground. Relay 26 operates thereby opening theringing circuit. Since relay 36 is operated, the operation of relay 26also connects the ground onconductor 19 through its inner lower frontcontact and the next-to-the-inner upper front contact of relay 36, overconductor 20, through brush 14 of line finder LF to the lower winding ofrelay 6 in the line circuit LC. Relay 6 operates thereby causing therelease of the cut-oif relay 4. With rela 4 released, the conductors ofline 1 are isconnetced from conductors 9 and 10 and from the line finderLFand are again'connected to the windings of line relay 2. Relay 2 againoperates thereby closing a circuit. from ground at its outer frontcontact to lock relay 6 operated. Talking battery is now supplied tostations A and B through the windings of relay 2. The line 1 is heldbusy during the conversation by ground connected to conductor 10 at theouter lower front contact of relay 6.

The aforementioned operation of relay 26 c was also effective to causethe release of re lay 28 and relay 28 disconnects ground from conductor19. Relay 37 now releases there by causing the release of relay 35. Theoperations of magnets 49 and 74 return the connector switch S0 and thecode switch CS to normal in the same manner as hereinbefore described.The line finder switch LF returns to normal when the ground isdisconnected from conductor 19. All switching equipment is thus freedfor use on another connection while the conversation between stations Aand B is taking place. When the receivers are replaced at both stations,relay 2 releases thereby causing the release of relay 6. The linecircuit LC is now normal, ready for use on another connection.

In case the subscriber at the called station fails to answer the call,the removal of the receiver at the calling station trips the ringing.The connector and line finder switches are then restored to normal ashereinbefore described and when the receiver is replaced at the callingstation the line circuit LC is also restored to normal.

What is claimed is:

1. In a telephone system, party lines, automatic switches, means forestablishing a connection from a calling subscriber on a line to acalled subscriber on the same line through said switches, meansresponsive to the establishing of said connection for ringing saidcalled subscriber, and means responsive to the called subscriberanswering said ringing for releasing said switches.

2. In a telephone system, party lines, automatic switches, means forestablishing a connection from a calling subscriber on a line to acalled subscriber on the same line through said switches, meansresponsive to the establishing of said connection for ringing saidcalled subscriber, and means responsive to the called subscriberanswering said ringing for releasing said switches and for connecting asource of talking battery to said party line for said calling and calledsubscriber.

3. In a telephone system, party lines, automatic switches, means forestablishing a connection from a calling subscriber on a line to acalled subscriber on the same line through said switches, meansresponsive to the establishing of said connection. for ringing saidcalled subscriber, a relay, means responsive to the called subscriberanswering said ringing for operating said relay, and

means responsive to the operation of said relay for releasing saidswitches.

4. In a telephone system, party lines, automatic switc es, means forestablishing a connection from a calling subscriber on a line to acalled subscriber on the same line through said switches, meansresponsive to the establishing of said connection for ringing saidcalled subscriber, a relay associated with one of said switches, a relayassociated with the party line of said calling and called subscribers,means responsive to the called subscriber answering said ringing foractuating said first mentioned relay, means responsive to the operationof said first mentioned relay for actuating said second mentioned relay,and means responsive to the operation of said second mentioned relay forreleasing said switches.

5. In a telephone system, party lines, automatic switches, means forestablishing a connection from a calling subscriber on a line to acalled subscriber on the same line through said switches, meansresponsive to the establishing of said connection for ringing saidcalled subscriber, a relay associated with one of said switches, a relayassociated with the party line of said calling and called subscribers,means responsive to the called subscriber answering said ringing foractuating said first mentioned relay, means responsive to the operationof said first mentloned relay for actuating said second mentioned relay,and means responsive to the operation of said second mentioned relay forreleasing said switches and for connect ng a sourceof talking battery tosaid party lines for said calling and called subscribers.

6. In a telephone system, lines each serving a plurality of subscribersstations, automatic switches for use in extending a connection from acalling to a called station, means responsive to the establishing ofsaid connection for ringing the called station, a relay associated withthe line of said calling station for operation if said calling andcalled stations are on the same line, means responsive to the removal ofthe receiver at one of the stations of said line for terminating theringing and for operating said relay, and means responsive to theoperation of said relay for releasing said switches and for establishinga busy condition for said line and for supplying talking battery to saidcalling and called stations.

7. In a telephone system, subscribers lines each serving a plurality ofstations, automatic equipment including means arranged to ring both thecalling and called stations on calls between stations on the same line,means for extending a calling line to said equipment, means individualto said line for supplying talking battery to the stations on said line,and means efiective in consequence of the removal of the receiver at oneof the stations on said line for causing the release of said automaticequipment and for operating said individual means.

8. In a telephone system, subscribers lines each serving a plurality ofstations, equipment including an automatic switch for extending aconnection to a called line, means associated with said switch andarranged to ring both the calling and called stations on calls betweenstations on the same line means for extending a calling line to saidswitch, means individual to said line for supplying talking battery tothe stations on said line, and means operative in consequence of theremoval of the receiver at one of the stations on said line for causingthe release of said automatic equipment and for rendering saidindividual means efl'ective.

In witness whereof, I hereunto subscribe my name this 28th day ofv June,1932.

RAY L. STOKELY.

